Within the field of silkscreen applications, a need exists for washing inks and other debris from screen printing plates. Removal of inks, and sometimes emulsions, is important in order to reuse screens. Means for cleaning screen printing plates include application of pressurized cleaning fluid against a face of each screen printing plate. The ink and any other debris is removed from the screen printing plate through either chemical action of the cleaning fluid, manual scrubbing force, or the hydraulic action of the pressurized fluid. Although various cleaning fluids are utilized, including water, preferred cleaning fluids comprise solvents of various chemical composition. Heretofore, preferred solvents included hydrocarbon content solvents and other chemical compositions which could create byproducts in the form of vapors having a potentially explosive content. Accordingly, the industry has required screen printing plate washing and cleaning machines which are explosion-proof. This has resulted in cleaning machines having very heavy structure and inefficient design. Indeed, these machines are typically constructed of metal, such as stainless steel. Such structures create numerous problems including corrosion concerns, chemical compatibility difficulties, location restrictions due to weight, and overall inconvenience relative to portability. The metal machines are also relatively expensive to manufacture.
As the technology relating to cleaning of screen printing plates has progressed, developments in the chemical composition of solvents have allowed movement toward greater use of biodegradable components. Use of biodegradable cleaning fluids or solvents in the screen printing plate cleaning cycle provides numerous advantages including lower volatility, water solubility, improved disposability, and overall decreased personal safety hazards. Moreover, governmental restrictions on toxic disposal of solvents and cleaning fluids often become less burdensome when utilizing biodegradable cleaning fluids. Whereas explosion proof structures are required with cleaning systems using potentially explosive solvents, a non-explosion-proof structure may be utilized with cleaning systems of a non-explosive nature.
What is needed therefore is an apparatus for cleaning screen printing plates which is constructed of substantially chemically inert materials relative to the chemical composition of solvents to be used, and which structure provides a lightweight sealed enclosure within which a screen printing plate may be inserted and spray cleaned.
What is further needed is a screen printing plate cleaning apparatus in the form of an enclosure having translucent wall materials conducive to more efficient inspection of screen printing plate cleanliness following a wash cycle.
What is further needed is a screen printing plate cleaning apparatus comprising efficient subsystems with fixed location automatic and programmable scanning spray heads and pneumatically driven and controlled pump means for providing power and drain capabilities to the cleaning apparatus.
What is even further needed is a screen printing plate cleaning apparatus comprising a plurality of fixed location scanning spray heads capable of alternating or switchable operation in order to maximize the efficient use of low power and low pressure pumping systems as well as to efficiently accommodate variously sized screen printing plates.
Other objects and advantages of the invention will appear from the following detailed description which, in connection with the accompanying drawings, discloses embodiments of the invention for purposes of illustration only and not for determination of the limits of the invention .